class_docstr: A helper class that represents input string that to be modified.
  
  Text that Sample contains parsed in data set,
  ``TextField`` provides multiple methods for Sample to modify.
  
  Support sentence level and word level modification,
  default using word level API.
docstr: Insert words before index and remove their mask value.
  
  :param int index:
      can be int indicate replace single item or their list like [1, 2, 3]
      can be list like (0,3) indicate replace items
          from 0 to 3(not included) or their list like [(0, 3), (5,6)]
      can be slice which would be convert to list.
  :param str|list|tuple new_items: items corresponding index.
  :return: new TextField object.
docstr_tok: ["Insert","words","before","index","and","remove","their","mask","value",".",":","param","int","index",":","can","be","int","indicate","replace","single","item","or","their","list","like","[","1",",","2",",","3","]","can","be","list","like","(","0,3",")","indicate","replace","items","from","0","to","3","(","not","included",")","or","their","list","like","[","(","0",",","3",")",",","(","5,6",")","]","can","be","slice","which","would","be","convert","to","list",".",":","param","str|list|tuple","new_items",":","items","corresponding","index",".",":","return",":","new","TextField","object","."]
code: def insert_after_index(self, index, new_items):
      r"""
      Insert words before index and remove their mask value.
  
      :param int index:
          can be int indicate replace single item or their list like [1, 2, 3]
          can be list like (0,3) indicate replace items
              from 0 to 3(not included) or their list like [(0, 3), (5,6)]
          can be slice which would be convert to list.
      :param str|list|tuple new_items: items corresponding index.
      :return: new TextField object.
  
      """
      return self.insert_after_indices([index], [new_items])
  
imports: from .field import Field
  from ....common.utils.list_op import *
  from ....common.preprocess.en_processor import EnProcessor
  from ....common.settings import ORIGIN, TASK_MASK, MODIFIED_MASK
label_desc: Use image node_id 16 for calling the TextField obj's underlying member method code with example usage: obj.insert_after_index(index, new_items) and returns: self